The prior art is replete with portable devices of the type described above that each carry a roll of pressure sensitive adhesive coated tape and a roll of sheet masking material and adhere the tape along the edge of the masking material to form the composite masking sheet as it is withdrawn from the device. U.S. Pat. Nos. 3,787,271; 4,379,019; 4,425,182; and 4,508,587 provide illustrative examples.
The portable device of this type described in U.S. Pat. No. 4,379,019 comprises a frame including a handle adapted for manual engagement to manipulate the device, and tape and masking material hubs mounted on the frame for rotation about spaced generally parallel axes. The tape hub receives the roll of tape and positions a first edge of the length of tape at a predetermined tape edge position axially with respect to the tape and masking material hubs, and the masking material hub receives the roll of masking material and positions a first edge of the length of masking material at a predetermined masking material edge position axially with respect to the hubs with the width of the length of tape extending from the tape edge position past the masking material edge position and the width of the length of masking material extending from the masking material edge position past the tape edge position. The device defines a path for the length of tape from the roll of tape, and a path for the length of masking material from the roll of masking material including a tape path portion from the roll of tape to the periphery of the roll of masking material and a common path portion beginning at the periphery of the roll of masking material where a portion of the tape along its first edge is adhered to a portion of the masking material along its first edge to form a composite masking sheet having opposite edges defined by the second edges of the lengths of tape and masking material. A portion of the coating of pressure sensitive adhesive exposed along the second edge on the length of tape can then be adhered along a surface to be masked to hold the composite masking sheet in a desired position.
When different combinations of tape widths and types of masking material are used on the device, it is sometimes desirable to have more or less of the tape adhered to the masking material. For example, when three quarter inch wide masking tape is used persons often prefer only about 3/8 inch or 0.95 centimeters of overlap between the tape and the masking material to expose more of the adhesive on the tape by which the composite masking sheet will be adhered to a substrate, whereas when wider masking tapes (e.g., up to two inch wide) are used persons often prefer more overlap (e.g., 1/2 inch or 1.27 centimeters of overlap) to insure good adhesion of the tape to the masking material. The device has been supplied with a flange around the tape hub against which the first edge of the tape on the roll is positioned spaced from a surface on the frame against which the first edge of the masking material in the roll is positioned to normally provide the larger of these overlaps; and a ring has been supplied with the device which can be positioned around the tape hub next to the flange to change the position of the first edge of tape along the hub and provide the smaller of these overlaps. While this works, the ring can become misplaced or lost, particularly if it is not always used.
Also, the tape hub used on the device described above has a generally circular peripheral surface around which the roll of tape is positioned that is defined by closely spaced axially extending ribs. This peripheral surface does not properly accept the nominally three inch diameter tape cores used in rolls of tape of both imperial specification (e.g., United States origin) and metric specification (e.g., European origin) because of the about 0.030 inch difference in their inner diameters. If the core in one of those rolls of tape slides over the tape hub with a proper friction fit, the core in the other is either too big to frictionally engage it, or too small to slide over it. Nor does that peripheral surface easily accommodate differences in the sizes of tape cores in rolls of tape that may result from tension in the tape wrapped about them or changes in humidity.